Improvement in electro-magnets



y No {119,176. Patented Sep. 19,1871.

UNITED STATES PATENT FFICE.

EMILE PREVOST, OF NEW YORK, N. N.

IMPROVEMENT IN ELECTRO-MAGNETS.

Specification forming part of Letters Patent No. 119,176, dated September 19, 1871.

To all whom t may concern:

Be it known that I, EMILE PREVOST, of the city, county, and State of New York, have invented a new and useful Improvement in Electro-Magnets 5 and I do hereby declare the following to be a full,v clear, and exact description thereof, which will enable those skilled in the art to make and use the same, reference being had to the accompanying drawing forming part oi' this specilication, which drawing, consisting or' one ligure, represents an electro-magnet made according to my invention.

rIhis invention relates to certain improvements in electro-magnets suitable for electromagnetic machines and apparatus for telegraphing, imparting motion, and other purposes where electro-magnets are required; and the object ot' the invention is to produce an electro-magnet which shall have greater` attracting and repelling power than electro-magnets or' equal size made in the ordinary manner.

In making an electromagnet according to my invention, I take a bar of iron of the best quality and of the requisite diameter, according to the surface desired, and bring it to the shape of a horseshoe, which form I lind to answer best; but when forging or bending it care must be taken not to overwerk or burn the metal. After each heat I immediately immerse it in a bath of 1nolten lead or fusible metal, wherein it is allowed to cool. Care must be taken to prevent the said bar from iloating ou the surface of the bath and thus coming in contact with the air. I repeat the operation of heating the bar, andthe subsequent cooling of the same in said bath, six or seven times. During the last reheating the te1nperature of the lead must be about the melting point, and I add .iiour of sulphur to the bath from time to time, until the bar bends with ease.

The bar of iron having been prepared as above described, and having been well polished after the last cooling, is next plunged into a bath o1" alcohol at an elevated temperature until the metal assumes a yellowish color, whereupon iinely divided sal-amoniae is to be added to the alcoholic bath, and the whole is allowed to cool as slowly as possible. After this it will be found that the bar or horseshoe when under the iniluence of an electric current will become powerfully attractive and repulsive.

In lapping' my improved electro-magnet l take a three-strand copper wirethat is say, a twisted wire made of three copper wires twisted together and with these combined wires I lap the horseshoe-shaped bar above described. For electro-magnets of comparativelyv small power six coils or layers will be suilicicnt, but for powerful magnets I employ ten of such coils or layers. The diameter or' the copper wire forlapping small magnets should be about one-sixteenth of an inch, but for large and powerful magnets one-eighth of an inch copper wire should be employed. One of the three twisted wires may be applied, if required, to an induction-coil whereby a return current toward the battery will be obtained at the moment of production or' the spark on the commutator.

W'hat I claim as new, and desire to secure by Letters Patent, is-

'Ihe process, substantially as above described, for treating and preparing bars for electroanagnets.

This specification signed by me this 21st day of December, 1869.

EMILE PREVOST. Vitnesses:

W. HAUEE, G. WAnLERs. 

